Numerous hydrocarbon conversion processes can be used to alter the structure or properties of hydrocarbon streams. Generally, such processes include isomerization from straight chain paraffinic or olefinic hydrocarbons to more highly branched hydrocarbons, dehydrogenation for producing olefinic or aromatic compounds, reformation to produce aromatics and motor fuels, alkylation to produce commodity chemical and motor fuels, transalkylation and others. Typically, such processes use catalysts to promote hydrocarbon conversion reactions. As the catalysts deactivate, it is generally desirable to regenerate them with a moving bed regeneration system. Such moving bed regeneration systems are known and exemplary systems, which also disclose the removal of chlorides from a regeneration flue gas stream, are disclosed in U.S. Pat. Nos. 5,837,636 (Sechrist et al.) and 6,034,018 (Sechrist et al.). Generally, the gas for combustion is recycled with a portion purged as a flue gas stream. Typically, these regeneration systems remove halogen-containing material, such as chlorides, from the combustion zone flue gas stream. Usually, the flue gas is passed through a cooler prior to being sent through a vessel, such as a disengaging hopper, that contains spent catalyst, which adsorbs chlorides from the flue gas. Subsequently, the flue gas can be discharged to the atmosphere and the spent catalyst may pass to the regeneration zone.
However, it is desirable to prevent gas entrained with the spent catalyst from the reaction zone from mixing with gas from the regeneration vessel. Particularly, the gas entrained with the catalyst can contain hydrogen and hydrocarbons and the gas from the regeneration zone can contain oxygen along with nitrogen, carbon dioxide, water, and chlorides. Sometimes, a flue gas cannot be passed through the catalyst-disengaging hopper without risking gas associated with the spent catalyst being forced through the catalyst transfer lines. As a result, the gas associated with the spent catalyst that can contain hydrogen may be forced into the combustion zone of the regeneration vessel. The presence of such a gas in the high temperature and oxygen environment of the combustion zone would be highly undesirable and could lead to an uncontrolled combustion in the regeneration vessel. Alternatively, it is also desirable to prevent gas from the combustion zone from mixing with gas from the catalyst-disengaging hopper, and possibly the hydrocarbon conversion zone.
Therefore, it would be beneficial to provide a mechanism to remove halogen-containing material, such as chlorides, from the flue gas from a regeneration vessel used in conjunction with a hydrocarbon conversion unit, and generally at the same time separate gases associated with the spent catalyst from reaction gases associated with the regeneration vessel.